Re: [PATCH] vfs: parse sloppy mount option in correct order

[Jeff Layton <jlayton@redhat.com>]

On Wed, 2022-09-28 at 09:09 +0800, Ian Kent wrote:
> From: Roberto Bergantinos Corpas <rbergant@redhat.com>
> 
> With addition of fs_context support, options string is parsed
> sequentially, if 'sloppy' option is not leftmost one, we may
> return ENOPARAM to userland if a non-valid option preceeds sloopy
> and mount will fail :
> 
> host# mount -o quota,sloppy 172.23.1.225:/share /mnt
> mount.nfs: an incorrect mount option was specified
> host# mount -o sloppy,quota 172.23.1.225:/share /mnt
> host#
> 
> This patch correct that behaviour so that sloppy takes precedence
> if specified anywhere on the string
> 
> changes since v1:
> - add a boolean to fs context and postpone error reporting until
>   parsing is done.
> 
> Signed-off-by: Roberto Bergantinos Corpas <rbergant@redhat.com>
> ---
>  fs/cifs/fs_context.c       |    4 ++--
>  fs/cifs/fs_context.h       |    1 -
>  fs/fs_context.c            |   14 ++++++++++++--
>  fs/nfs/fs_context.c        |    5 +++--
>  fs/nfs/internal.h          |    1 -
>  include/linux/fs_context.h |    2 ++
>  6 files changed, 19 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c
> index 0e13dec86b25..32c3fdd7d27a 100644
> --- a/fs/cifs/fs_context.c
> +++ b/fs/cifs/fs_context.c
> @@ -864,7 +864,7 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
>  	if (!skip_parsing) {
>  		opt = fs_parse(fc, smb3_fs_parameters, param, &result);
>  		if (opt < 0)
> -			return ctx->sloppy ? 1 : opt;
> +			return fc->sloppy ? 1 : opt;
>  	}
>  
>  	switch (opt) {
> @@ -1420,7 +1420,7 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
>  		ctx->multiuser = true;
>  		break;
>  	case Opt_sloppy:
> -		ctx->sloppy = true;
> +		fc->sloppy = true;
>  		break;
>  	case Opt_nosharesock:
>  		ctx->nosharesock = true;
> diff --git a/fs/cifs/fs_context.h b/fs/cifs/fs_context.h
> index bbaee4c2281f..75e4c41466fa 100644
> --- a/fs/cifs/fs_context.h
> +++ b/fs/cifs/fs_context.h
> @@ -157,7 +157,6 @@ struct smb3_fs_context {
>  	bool uid_specified;
>  	bool cruid_specified;
>  	bool gid_specified;
> -	bool sloppy;
>  	bool got_ip;
>  	bool got_version;
>  	bool got_rsize;
> diff --git a/fs/fs_context.c b/fs/fs_context.c
> index df04e5fc6d66..911a36bf2226 100644
> --- a/fs/fs_context.c
> +++ b/fs/fs_context.c
> @@ -157,8 +157,15 @@ int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param)
>  	if (ret != -ENOPARAM)
>  		return ret;
>  
> -	return invalf(fc, "%s: Unknown parameter '%s'",
> -		      fc->fs_type->name, param->key);
> +	/* We got an invalid parameter, but sloppy may have been specified
> +	 * later on param string.
> +	 * Let's wait to process whole params to return EINVAL.
> +	 */
> +
> +	fc->param_inval = true;
> +	errorf(fc, "%s: Unknown parameter '%s'", fc->fs_type->name, param->key);

Is it correct to store an error message when we don't know whether
"sloppy" has been specified yet?

> +
> +	return 0;
>  }
>  EXPORT_SYMBOL(vfs_parse_fs_param);
>  
> @@ -234,6 +241,9 @@ int generic_parse_monolithic(struct fs_context *fc, void *data)
>  		}
>  	}
>  
> +	if (!fc->sloppy && fc->param_inval)
> +		ret = -EINVAL;
> +
>  	return ret;
>  }
>  EXPORT_SYMBOL(generic_parse_monolithic);
> diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
> index 4da701fd1424..09da63cc84f7 100644
> --- a/fs/nfs/fs_context.c
> +++ b/fs/nfs/fs_context.c
> @@ -485,7 +485,7 @@ static int nfs_fs_context_parse_param(struct fs_context *fc,
>  
>  	opt = fs_parse(fc, nfs_fs_parameters, param, &result);
>  	if (opt < 0)
> -		return (opt == -ENOPARAM && ctx->sloppy) ? 1 : opt;
> +		return (opt == -ENOPARAM && fc->sloppy) ? 1 : opt;
>  
>  	if (fc->security)
>  		ctx->has_sec_mnt_opts = 1;
> @@ -853,7 +853,8 @@ static int nfs_fs_context_parse_param(struct fs_context *fc,
>  		 * Special options
>  		 */
>  	case Opt_sloppy:
> -		ctx->sloppy = true;
> +		fc->sloppy = true;
> +		dfprintk(MOUNT, "NFS:   relaxing parsing rules\n");
>  		break;
>  	}
>  
> diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
> index 898dd95bc7a7..83552def96f1 100644
> --- a/fs/nfs/internal.h
> +++ b/fs/nfs/internal.h
> @@ -90,7 +90,6 @@ struct nfs_fs_context {
>  	bool			internal;
>  	bool			skip_reconfig_option_check;
>  	bool			need_mount;
> -	bool			sloppy;
>  	unsigned int		flags;		/* NFS{,4}_MOUNT_* flags */
>  	unsigned int		rsize, wsize;
>  	unsigned int		timeo, retrans;
> diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h
> index ff1375a16c8c..d91d42bc06ce 100644
> --- a/include/linux/fs_context.h
> +++ b/include/linux/fs_context.h
> @@ -111,6 +111,8 @@ struct fs_context {
>  	bool			need_free:1;	/* Need to call ops->free() */
>  	bool			global:1;	/* Goes into &init_user_ns */
>  	bool			oldapi:1;	/* Coming from mount(2) */
> +	bool                    sloppy:1;       /* If fs support it and was specified */
> +	bool                    param_inval:1;  /* If set, check sloppy value */
>  };
>  
>  struct fs_context_operations {
> 
> 

Overall, the patch looks reasonable though.
-- 
Jeff Layton <jlayton@redhat.com>